LINQ Query Dynamic Column

As an alternate we can use the itemArray from the row

(From d in dtData.AsEnumerable
Let rchk = d.ItemArray.Select(Function (x) CDate(x.toString.trim)).Any(Function (d) d.Day = 5 AndAlso d.Month = 5)
Where rchk
Select r = d).CopyToDataTable

In case we do expect empty filter result we can handle as described here:
:ambulance: :sos: [FirstAid] Handling of The source contains no DataRows exception - News / Tutorials - UiPath Community Forum